A standardized method for determination of iodine in serum by inductively coupled plasma mass spectrometry / 中华地方病学杂志

ABSTRACT

Objective:To develop a standard method for determination of iodine in serum by inductively coupled plasma mass spectrometry (ICP-MS).Methods:A direct dilution sampling-ICP-MS method for measuring iodine in serum was developed with 2.0 g/L ascorbic acid-1.0 g/L ammonium chloride-0.10% ethanolamine-1.0% ethanol as diluent; the standard solutions and the serum samples were all diluted in a ratio of 1 19 (sample diluent) before testing with Re as internal standard element. Methodological evaluation of a new method was done through standard curve linearity, sample detection limit, precision and accuracy in determining serum iodine. And the results were compared with the results determined by current standard method for determination of iodine in serum [arsenic-cerium catalytic spectrophotometry, hereinafter referred to as the standard method (WS/T 572-2017)].Results:The following data were obtained by testing the method in six laboratories. The linear range of the calibration curve was 0 - 300 μg/L and the linear correlative coefficients were 0.999 9 - 1.000 0 ( n = 70). The detection limit for serum iodine was 0.2 to 1.3 μg/L (0.20 ml of serum was tested). Precision the average intra assay coefficient of variation ( CV) was 0.6% with a range of 0.2% - 1.6% when measuring 31 serum samples; the average inter assay CV was 1.3% with a range of 0.3% - 2.4% when measuring 34 serum samples. Accuracy the average recovery was 100.3% with a range of 93.9% - 105.6% when measuring 36 serum samples. No significant difference was found between the results of the 116 serum samples determined by the new method and the standard method ( P > 0.05). Conclusions:The new method has a good standard curve linearity, high sensitivity, good precision, accuracy and is easy to be used and quickly to be analyzed of the test results, and is suitable for widely application in determining serum iodine.